1. Field of the Invention
The present invention is directed towards the preparation of compounds of the general formula (I): 
Such compounds are prepared in particular by means of an enzymatic process from hydantoins of the general formula (II): 
2. Description of Related Art
Compounds of formula (I) are suitable intermediates for the preparation of pharmaceuticals described in U.S. Pat. No. 5552397, WO 9738705 and in J. Med. Chem. 42, 305 (1999).
J. Med. Chem. 42, 305 (1999) mentions a synthesis route for the preparation of a structural unitxe2x80x94an xcex1-amino-xcex5-caprolactam derivativexe2x80x94of the pharmaceutically active compounds. However, that structural unit is obtained with the aid of expensive reagents in a process that is rather disadvantageous for a robust commercial process.
The preparation of compounds such as (I) from hydantoins such as (II) by means of Arthrobacter sp. is already known from JP 99206397. However, that document does not describe the advantageous racemisation.
The conversion of hydantoins by means of hydantoinases and specific carbamoylases is already known from DE19529211.1. The spontaneous chemical racemisation of hydantoins for the preparation of enantiomerically enriched amino acids is to be found in DE-P4137581.5-44.
Accordingly, one object of the present invention is to provide an enzymatic process for the preparation of the desired compounds of formulae (I), that is a simpler, more efficient, and less costly process suitable for large-scale commercial or industrial applications.
Another object of the invention is to provide a process for providing an allysine acetal in high yield and with a high degree of optical purity, for instance L-allysine acetal in a yield of about 85% or more, preferably at least 90% and most preferably  greater than 95%, and with an optical purity of at least 90%, preferably at least 95%, and most preferably  greater than 99% ee.
Yet another object of the invention is to provide a process that uses a total cell catalyst comprising a cell that has a gene encoding a hydantoin racemase, a hydantoinase and an L- or D-specific carbamoylase. For instance, a total cell catalyst comprising an L-specific carbamoylase.
Products and compositions comprising compounds of general formulae (I) and having a high degree of optical purity are advantageously used as intermediates for producing pharmacologically active products, or directly in pharmacological products.
Other objects of the invention are described or may be inferred from the following detailed description.